A contactless thin-layered torque sensor with fully-digital signal processing circuit is proposed in this work. The mechanical structure of the torque sensor is an orange-slice-alike flexible body. Two links, beforehand aligned, with B/W stripes play the role of optical grating by resolution 1° as no any torque applied to the shaft. As long as the orange-slice-alike flexible body, sandwiched by the aforesaid links, is subject to an external torque applied, a twisted angle is induced between the two thin photo-grating discs. Two sets of photo detector cooperate with the two discs with optical gratings to generate two pulse sequences. Therefore, a time delay between these two pulse sequences can be acquired as long as the shaft is twisted by a torque. A counter IC is employed to quantify this time delay in terms of the torque applied, and the time period, in terms of rotational speed of shaft. One of merits of the proposed torque sensor is: real-time measurement on torque applied becomes feasible even if the shaft, subject to external torque, is rotating at high speed. Another advantage of the fully-digital signal processing circuit is: no need to conduct A/D conversion and free of noise, cross-talk and EMI (Electromagnetic Interference).